A transmission for a lawn mower, for transmitting an output of a drive source to a driving wheel, the transmission including a speed-change transmission device and a power transmission device movably coupled to the speed-change transmission device. The power transmission device includes a first power transmission device coupled to the speed-change transmission device and a second power transmission device to which the driving wheel is coupled, and the first power transmission device and the second power transmission device are movably coupled to each other.

A transmission for a lawn mower, for transmitting an output of a drive source to a driving wheel, the transmission including a speed-change transmission device and a power transmission device movably coupled to the speed-change transmission device. The power transmission device includes a first power transmission device coupled to the speed-change transmission device and a second power transmission device to which the driving wheel is coupled, and the first power transmission device and the second power transmission device are movably coupled to each other.

When a contact area with a chain guide is reduced to a small area by forming a back surface of a link plate into a convex portion having a round shape or the like, a friction coefficient in a fluid lubrication region is reduced (region E). A coating film containing 10% or more of chromium is formed on the link plate. A friction modifier made of a molybdenum compound such as MoDTC and added to a lubricating oil promotes generation of MoS.sub.2 by the chromium coating film, and prevents an increase in the friction coefficient in a boundary lubrication region.

When a contact area with a chain guide is reduced to a small area by forming a back surface of a link plate into a convex portion having a round shape or the like, a friction coefficient in a fluid lubrication region is reduced (region E). A coating film containing 10% or more of chromium is formed on the link plate. A friction modifier made of a molybdenum compound such as MoDTC and added to a lubricating oil promotes generation of MoS.sub.2 by the chromium coating film, and prevents an increase in the friction coefficient in a boundary lubrication region.

An internal combustion engine includes exhaust-side and intake-side variable valve timing mechanisms, an oil passage defined in the cylinder head, an exhaust-side connection passage that branches from the oil passage to conduct oil to the exhaust-side variable valve timing mechanism, and an intake-side connection passage that branches from the oil passage to conduct oil to the intake-side variable valve timing mechanism. The connection passage that conducts oil to one of the exhaust-side variable valve timing mechanism and the intake-side variable valve timing mechanism that has a greater amount of oil leakage when oil having the same pressure is supplied to the variable valve timing mechanisms to operate the variable valve timing mechanisms is located at a downstream side in the oil passage of the connection passage that conducts oil to the variable valve timing mechanism that has a smaller amount of oil leakage.

An internal combustion engine includes exhaust-side and intake-side variable valve timing mechanisms, an oil passage defined in the cylinder head, an exhaust-side connection passage that branches from the oil passage to conduct oil to the exhaust-side variable valve timing mechanism, and an intake-side connection passage that branches from the oil passage to conduct oil to the intake-side variable valve timing mechanism. The connection passage that conducts oil to one of the exhaust-side variable valve timing mechanism and the intake-side variable valve timing mechanism that has a greater amount of oil leakage when oil having the same pressure is supplied to the variable valve timing mechanisms to operate the variable valve timing mechanisms is located at a downstream side in the oil passage of the connection passage that conducts oil to the variable valve timing mechanism that has a smaller amount of oil leakage.

A chain guide includes a contact guide portion that comes into contact with a chain and guides the chain, and a vibration control portion having a zero-touch surface extending along a travel line of the chain.

A chain guide includes a contact guide portion that comes into contact with a chain and guides the chain, and a vibration control portion having a zero-touch surface extending along a travel line of the chain.

The invention relates to the control mechanism developed for continuously variable transmission systems which are chain/belt-driven and which are used in the vehicles with electrical, hybrid and conventional internal combustion engine as an automatic gearbox system in the automotive industry.

A mechanical system with a double-sided chain, composed of a driving wheel (S1), a tensioner wheel (S2) for the chain (1), a driven wheel (S3) and a chain (1), which winds around the wheels (S1) and (S2), and engages the wheel (S3) on its outer side, characterized in that the wheel centres (S1), (S2) and (S3) are not collinear, whereas the position of wheel axis (S2) in relation to wheel axis (S1) and (S3) determines the line of operation of chain (1) and determines the optimal angle alpha between the direction of the force vector F and the perpendicular to the straight line joining the centres of tensioner wheel (S2) and driven wheel (S3), and passing through point (B) where force F1 is applied. while the value of the angle alpha is equal 15 degrees.